# NTSB GAA17CA376: Robinson Helicopter R22, N8361N, Kelso, WA, June 30, 2017

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Data collection · Final report
- Date: June 30, 2017, 13:56 local (20:56 UTC)
- Place: Kelso, WA
- Coordinates: 46.102779, -122.511947 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.1028&lon=-122.5119&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing: Loss of tail rotor effectiveness](https://openairdocs.org/ntsb-events/242)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report December 15, 2017
- Report: Approved by Office Director
- NTSB office: General Aviation Accidents
- Parties: FAA
- NTSB case key (mKey): 95472
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=GAA17CA376
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95472/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95472
- Page: https://openairdocs.org/ntsb/GAA17CA376

## Probable cause

The flight instructor’s delayed remedial action, which resulted in a loss of helicopter control due to a loss of tail rotor effectiveness.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Action: delayed action](https://openairdocs.org/ntsb-findings/02041025): Personnel issues › Action/decision · Instructor/check pilot (probable cause); cases with it: [Robinson Helicopter R22 BETA, 35 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md?model=7640110), [All aircraft, 894 cases](https://openairdocs.org/ntsb-findings/02041025/cases.md)
- [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Instructor/check pilot (probable cause); cases with it: [Robinson Helicopter R22 BETA, 96 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=7640110), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md)
- [Performance/control parameters: prop/rotor parameters](https://openairdocs.org/ntsb-findings/01062052): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [Robinson Helicopter R22 BETA, 37 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md?model=7640110), [All aircraft, 182 cases](https://openairdocs.org/ntsb-findings/01062052/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Landing: Loss of tail rotor effectiveness](https://openairdocs.org/ntsb-events/242) (defining event); cases with it: [Robinson Helicopter R22 BETA, 10 cases](https://openairdocs.org/ntsb-events/242/sequence.md?model=7640110), [All aircraft, 100 cases](https://openairdocs.org/ntsb-events/242/sequence.md)
- [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Robinson Helicopter R22 BETA, 85 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=7640110), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)

## Analysis

The flight instructor reported that he was providing instruction to a student pilot in the helicopter during a cross-country flight. During the flight, the instructor asked the student to perform a "land as soon as possible" emergency procedure. The student pilot approached the hillside landing site from the south. The wind was out of the west about 8 to 10 knots, which resulted in a left crosswind for the landing. The student pilot reported that, during the approach, the instructor told him he "needed more left pedal." The helicopter descended and decelerated below effective translational lift (ETL). According to the Federal Aviation Administration's (FAA) 8083-21A, the Helicopter Flying Handbook, pg. 2-20, para. 2, ETL occurs between 16 and 24 knots. The student pilot reported that, "We descended below ETL, maybe 10 feet off the ground and still descending. By this point we were what I perceived to be straight, and the instructor took the controls. From what I could tell, he used forward cyclic and left pedal immediately. It was too late." The flight instructor reported that, "As we came closer to our landing spot and began to slow down, I felt that the nose of the helicopter was not pointed far enough into the wind (we were out of trim). I took the flight controls right as we slowed below ETL. The helicopter started to develop a hard right yaw and I immediately gave full forward cyclic." The helicopter developed an uncontrollable rapid right yaw and spun about two revolutions. The helicopter touched down on the skids and rolled onto its left side. The helicopter sustained substantial damage to the tail rotor drive shaft and the main and tail rotor blades. The student pilot and flight instructor reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. According to the FAA's Helicopter Flying Handbook (FAA-8083-21A), the Helicopter Instructor's Flying Handbook (FAA-8083-4), and Advisory Circular (AC) 90-95, "Unanticipated Rapid Right Yaw in Helicopters," the loss of tail rotor effectiveness (LTE) is a "critical, low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control." AC 90-95 defined flight characteristics and wind azimuths associated with LTE and stated that the tail rotor vortex ring state occurs during left crosswinds when the relative wind azimuth is from 210° to 330°" and that "winds within this region will result in the development of the vortex ring state of the tail rotor." AC 90-95 also stated that, for all wind azimuths, the loss of ETL is associated with LTE as it "results in increased power demands and additional anti-torque requirements."

## Factual narrative

The helicopter flight instructor reported that he was providing instruction to a student pilot during a cross country flight. During the flight, the instructor asked the student to perform a land as soon as possible emergency procedure. The student pilot approached the hillside, landing site from the south. The wind was out of the west and the helicopter descended and decelerated below effective translational lift (ETL). According to the FAA 8083-21A, The Helicopter Flying Handbook, pg. 2-20, para. 2, ETL occurs between 16 and 24 knots. The student pilot reported that, "We descended below ETL, maybe 10 feet off the ground and still descending. By this point we were what I perceived to be straight, and the instructor took the controls. From what I could tell, he used forward cyclic and left pedal immediately. It was too late." The instructor reported that, "I took the flight controls right as we slowed below ETL. The helicopter started to develop a hard right yaw and I immediately gave full forward cyclic." The helicopter developed an uncontrollable rapid right yaw and spun about two revolutions. The helicopter touched down on the skids and rolled on to its left side. The helicopter sustained substantial damage to the tail rotor drive shaft, the main and tail rotor blades. The pilot reported that there were no preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. According to the Federal Aviation Administration Helicopter Flying Handbook (FAA-8083-21A) and The Helicopter Instructors Flying Handbook (FAA-8083-4) and Advisory Circular (AC) 90-95 Unanticipated rapid right yaw: Loss of Tail Rotor Effectiveness (LTE) is a critical; low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control. AC 90-95 Section 7.d.3. (page 7) defines flight characteristics and wind azimuths associated with LTE. It states that tail rotor vortex ring state occurs when the wind is out of (210° to 330°). 1. Winds within this region will result in the development of the vortex ring state of the tail rotor.

## Aircraft

- Registration: [N8361N](https://openairdocs.org/deregistered/N8361N-2019-06-12), registration cancelled 2019-06-12, S/N 2901, built 1998 (OpenAirDocs)
- Reported make and model: ROBINSON HELICOPTER R22
- Registry model: [Robinson Helicopter R22 BETA](https://openairdocs.org/model/robinson-helicopter-r22-beta) (registry code 7640110) (OpenAirDocs)
- Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 2901
- Year built: 1994
- Airframe hours: 7725
- Engines: LYCOMING O-320 145 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Hillsboro Aero Academy
- Registered owner: Hillsboro Aero Academy
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, May 31, 2017
- Departed: W27, Woodland, OR
- Destination: KOLM, Olympia, WA
- Equipment: ADS-B

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Flight instructor; age 27; injuries: minor; flight instructor, commercial; instrument ratings: helicopter; medical: class 2, without waivers/limitations; last flight review November 20, 2016; seat: left; restraint: 3-point; flight hours: 815 total, 745 in this make and model, 750 as pilot in command, 86 in the last 90 days, 24 in the last 30 days, 0 in the last 24 hours
- Student pilot; age 27; injuries: minor; student; medical: class 2, without waivers/limitations; seat: right; restraint: 3-point; flight hours: 96 total, 96 in this make and model, 5 as pilot in command, 39 in the last 90 days, 14 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: 800 ft broken
- Temperature: 57 °F, dew point 55 °F
- Altimeter: 30.07 inHg
- Observed at: KKLS, 16 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20170630008759A](https://openairdocs.org/incident/20170630008759A), Jun 30, 2017: Robinson Helicopter R22 BETA, Kelso, WA, Substantial damage. During training flight with CFI and student. CFI instructed student to pick an off airport landing site for emergency landing. Student selected road in clear…

## Docket (3 files)

The files NTSB released with the investigation on November 7, 2017, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95472. 2.1 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 - CFI (item 1, .PDF, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457803&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1%20-%20CFI-Master.PDF
- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 - SP (item 2, .PDF, 604 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457804&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1%20-%20SP-Master.PDF
- Photo (Courtesy of FAA) (item 3, .PDF, 1 photo, 165 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40457805&FileExtension=.PDF&FileName=Photo%20(Courtesy%20of%20FAA)-Master.PDF

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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